Vessel sealing instrument with multiple electrode configurations

ABSTRACT

An electrode assembly for use with an instrument for sealing and cutting vessels and/or tissue is provided. The assembly includes a pair of opposing first and second jaw members. Each jaw member includes at least one electrically conductive tissue sealing surfaces extending along a length thereof. Each tissue sealing surface is adapted to connect to a source of electrosurgical energy to effect a tissue seal. An insulator is disposed adjacent to the at least one the electrically conductive sealing surfaces. The jaw members include an electrically conductive cutting element which effectively cuts tissue within pre-defined cutting zone between the jaw members. The polarity of the cutting element and electrically conductive sealing surfaces may be manipulated depending upon whether tissue sealing or tissue cutting is desired.

TECHNICAL FIELD

The present disclosure relates to a forceps used for both endoscopic andopen surgical procedures that includes an electrode assembly that allowsa user to selectively seal and/or cut tissue. More particularly, thepresent disclosure relates to a forceps that applies a uniquecombination of mechanical clamping pressure and electrosurgical energyto effectively seal and sever tissue between sealed tissue areas.

BACKGROUND

Open or endoscopic electrosurgical forceps utilize both mechanicalclamping action and electrical energy to effect hemostasis. Theelectrode of each opposing jaw member is charged to a different electricpotential such that when the jaw members grasp tissue, electrical energycan be selectively transferred through the tissue. A surgeon can eithercauterize, coagulate/desiccate and/or simply reduce or slow bleeding, bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied between the electrodes and through the tissue.

Certain surgical procedures require more than simply cauterizing tissueand rely on the combination of clamping pressure, electrosurgical energyand gap distance to “seal” tissue, vessels and certain vascular bundles.More particularly, vessel sealing or tissue sealing is arecently-developed technology that utilizes a unique combination ofradiofrequency energy, clamping pressure and precise control of gapdistance (i.e., distance between opposing jaw members when closed abouttissue) to effectively seal or fuse tissue between two opposing jawmembers or sealing plates. Vessel or tissue sealing is more than“cauterization”, which involves the use of heat to destroy tissue (alsocalled “diathermy” or “electrodiathermy”). Vessel sealing is also morethan “coagulation”, which is the process of desiccating tissue whereinthe tissue cells are ruptured and dried. “Vessel sealing” is defined asthe process of liquefying the collagen, elastin and ground substances inthe tissue so that the tissue reforms into a fused mass withsignificantly-reduced demarcation between the opposing tissuestructures.

To effectively seal tissue or vessels, especially thick tissue and largevessels, two predominant mechanical parameters must be accuratelycontrolled: 1) the pressure applied to the vessel; and 2) the gapdistance between the conductive tissue contacting surfaces (electrodes).Both of these parameters are affected by the thickness of the vessel ortissue being sealed. Accurate application of pressure is important forseveral reasons: to oppose the walls of the vessel; to reduce the tissueimpedance to a low enough value that allows enough electrosurgicalenergy through the tissue; to overcome the forces of expansion duringtissue heating; and to contribute to the end tissue thickness, which isan indication of a good seal. It has been determined that a typicalfused vessel wall is optimum between about 0.001 and about 0.006 inches.Below this range, the seal may shred or tear and above this range thetissue may not be properly or effectively sealed.

With respect to smaller vessels, the pressure applied becomes lessrelevant and the gap distance between the electrically conductivesurfaces becomes more significant for effective sealing. In other words,the chances of the two electrically conductive surfaces touching duringactivation increases as the tissue thickness and the vessels becomesmaller.

Typically, and particularly with respect to endoscopic electrosurgicalprocedures, once a vessel is sealed, the surgeon has to remove thesealing instrument from the operative site, substitute a new instrumentthrough the cannula and accurately sever the vessel along the newlyformed tissue seal. This additional step may be both time consuming(particularly when sealing a significant number of vessels) and maycontribute to imprecise separation of the tissue along the sealing linedue to the misalignment or misplacement of the severing instrument alongthe center of the tissue seal.

Several attempts have been made to design an instrument thatincorporates a knife or blade member that effectively severs the tissueafter forming a tissue seal. For example, commonly-owned U.S.application Ser. Nos. 10/472,295, 10/460,942 and 10/991,157 all discloseinstruments that include a mechanical cutting mechanism for selectivelycutting tissue along a tissue seal. These instruments have enjoyed greatsuccess in the operating field.

Sealing and electrically cutting on the same instrument is a recentlydeveloped technology that provides different advantages overmechanically cutting tissue. However, electrical cutting of tissue hasproven difficult for manufacturing due to the dimensions betweenelectrodes being relatively small. The electrodes may produce heatformation and electrical charging during the seal cycle thatdetrimentally affects the cut performance. This may manifest itself bydamaging tissue within the cut zone and minimizing hydration by forcingconductive fluids from the cut area.

SUMMARY

Accordingly, the present disclosure is directed to an electrode assemblyfor use with an instrument for sealing and cutting vessels and/ortissue. In one embodiment the assembly includes a pair of opposing firstand second jaw members at least one of which being movable relative tothe other from a first position wherein the jaw members are disposed inspaced relation relative to one another to a second position wherein thejaw members cooperate to grasp tissue therebetween.

Each jaw member includes at least one electrically conductive tissuesealing surface extending along a length thereof. Each tissue sealingsurface is adapted to connect to a source of electrosurgical energy suchthat the tissue sealing surfaces are capable of conductingelectrosurgical energy through tissue held therebetween to effect aseal. An insulator is included which is disposed adjacent to the atleast one electrically conductive sealing surfaces.

The first jaw member includes an electrically conductive cutting elementdisposed within the insulator of the first jaw member, the electricallyconductive cutting element disposed in general vertical registration tothe insulator on the second jaw member to define at least one cuttingzone between the electrically conductive tissue sealing surface(s) andthe cutting element.

The cutting element and the pair of spaced apart electrically conductivesealing surfaces on the first jaw member are energized to a firstpotential during a sealing process and the electrically conductivesealing surface(s) on the first jaw member are energized to a differentpotential from the corresponding electrically conductive sealingsurface(s) on the second jaw member such that electrosurgical energy canbe transferred through the tissue to effect a tissue seal.

The cutting element is configured to maintain the same potential duringa cutting stage. The electrically conductive sealing surface(s) on thefirst jaw member and the corresponding electrically conductive sealingsurface(s) on the second jaw member are energized to a differentpotential than the cutting element such that electrosurgical energy canbe transferred through the tissue to effect a tissue cut.

Another embodiment of the present disclosure includes an electrodeassembly for use with an instrument for sealing and cutting vesselsand/or tissue. The assembly includes a pair of opposing first and secondjaw members at least one of which is movable relative to the other froma first position wherein the jaw members are disposed in spaced relationrelative to one another to a second position wherein the jaw memberscooperate to grasp tissue therebetween.

Each jaw member includes at least one electrically conductive tissuesealing surface extending along a length thereof. Each tissue sealingsurface is adapted to connect to a source of electrosurgical energy suchthat the tissue sealing surfaces are capable of conductingelectrosurgical energy through tissue held therebetween to effect aseal. An insulator is included which is disposed adjacent to theelectrically conductive sealing surface(s).

The first jaw member includes an electrically conductive cutting elementdisposed within the insulator of the first jaw member. The electricallyconductive cutting element is disposed in general vertical registrationto the insulator on the second jaw member defining at least one cuttingzone between the electrically conductive tissue sealing surface(s) andthe cutting element.

The electrically conductive tissue sealing surface(s) includes at leastone sealing section operatively connected to at least one flange. Theflange(s) is configured to control a gap distance between the opposingelectrically conductive tissue sealing surfaces. The insulator isdimensioned to reduce stray currents and heat dissipation inwardlytowards the cutting zone(s).

An insulator may be included having a first portion which extendsbetween the flange(s) and the electrically conductive cutting element(s)to a point in general horizontal registration with the electricallyconductive sealing surface(s).

The first jaw member may include an electrically conductive cuttingelement disposed within the insulator of the first jaw member. Theelectrically conductive cutting element may be disposed in generalvertical registration to the insulator on the second jaw member todefine a cutting zone between the electrically conductive tissue sealingsurface and the cutting element.

The electrically conductive tissue sealing surface may includes at leastone sealing section operatively connected to a corresponding flange(s).The flange(s) extends from an inner leg of the sealing section and isconfigured to control a gap distance between the electrically conductivetissue sealing surfaces.

The cutting element and the pair of spaced apart electrically conductivesealing surfaces on the first jaw member are energized to a firstpotential during a sealing process. During sealing, the electricallyconductive sealing surface(s) on the first jaw member are energized to adifferent potential from the corresponding electrically conductivesealing surface(s) on the second jaw member such that electrosurgicalenergy can be transferred through the tissue to effect a tissue seal.

During cutting, the cutting element is configured to maintain the samepotential during the cutting stage and the electrically conductivesealing surface(s) on the first jaw member and the correspondingelectrically conductive sealing surface(s) on the second jaw member areenergized to a different potential than the cutting element such thatelectrosurgical energy can be transferred through the tissue to effect atissue cut.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1A shows a right, perspective view of an endoscopic bipolar forcepshaving a housing, a shaft and a pair of jaw members affixed to a distalend thereof, the jaw members including an electrode assembly disposedtherebetween;

FIG. 1B shows a left, perspective view of an open bipolar forcepsshowing a pair of first and second shafts each having a jaw memberaffixed to a distal end thereof with an electrode assembly disposedtherebetween;

FIG. 2 shows a cross-sectional view of a vessel sealing instrumentshowing one embodiment of a cut zone configuration;

FIG. 3 shows a cross-sectional view of an alternate embodiment of avessel sealing instrument of the present disclosure having one cut zone;

FIG. 4 shows a cross-sectional view of one embodiment of electrodesarranged in a particular seal configuration;

FIG. 5 shows a cross-sectional view of another embodiment of electrodesarranged in a particular seal configuration;

FIG. 6 shows a cross-sectional view of another embodiment of the cutzone configuration of the vessel sealing instrument according to thepresent disclosure; and

FIG. 7 shows a cross-sectional view of yet another embodiment of the cutzone configuration of the vessel sealing instrument of the presentdisclosure.

DETAILED DESCRIPTION

For the purposes herein, vessel/tissue cutting or vessel/tissue divisionis believed to occur when heating of the vessel/tissue leads toexpansion of intracellular and/or extra-cellular fluid, which may beaccompanied by cellular vaporization, desiccation, fragmentation,collapse and/or shrinkage along a so-called “cut zone” in thevessel/tissue. By focusing the electrosurgical energy and heating in thecut zone, the cellular reactions are localized creating a fissure.Localization is achieved by regulating the vessel/tissue condition andenergy delivery, which may be controlled by utilizing one or more of thevarious geometrical electrode and insulator configurations describedherein. The cut process may also be controlled by utilizing a generatorand feedback algorithm (and one or more of the hereindescribedgeometrical configurations of the electrode and insulator assemblies),which increases the localization and maximizes the so-called “cuttingeffect”.

For example, the below-described factors may contribute and/or enhancevessel/tissue division using electrosurgical energy. Each of the factorsdescribed below may be employed individually or in any combination toachieve a desired cutting effect. For the purposes herein the term “cuteffect” or “cutting effect” refers to the actual division of tissue byone or more of the electrical or electro-mechanical methods ormechanisms described below. The term “cutting zone” or “cut zone” refersto the region of vessel/tissue where cutting will take place. The term“cutting process” refers to steps that are implemented before, duringand/or after vessel/tissue division that tend to influence thevessel/tissue as part of achieving the cut effect.

For the purposes herein the terms “tissue” and “vessel” may be usedinterchangeably since it is believed that the present disclosure may beemployed to seal and cut tissue or seal and cut vessels utilizing thesame inventive principles described herein.

It is believed that the following factors either alone or incombination, play an important role in dividing tissue:

-   -   Localizing or focusing electrosurgical energy in the cut zone        during the cutting process while minimizing energy effects to        surrounding tissues;    -   Focusing the power density in the cut zone during the cutting        process;    -   Creating an area of increased temperature in the cut zone during        the cutting process (e.g., heating that occurs within the tissue        or heating the tissue directly with a heat source);    -   Pulsing the energy delivery to influence the tissue in or around        the cut zone. “Pulsing” involves as a combination of an “on”        time and “off” time during which the energy is applied and then        removed repeatedly at any number of intervals for any amount of        time. The pulse “on” and “off” time may vary between pulses. The        pulse “on” typically refers to a state of higher power delivery        and pulse “off” typically refers to a state of lower power        delivery;    -   Spiking the energy delivery creates a momentary condition of        high energy application with an intent to influence the tissue        in or around the cut zone during the cut process. The momentary        condition may be varied to create periods of high energy        application;    -   Conditioning the tissue before or during the cutting process to        create more favorable tissue conditions for cutting. This        includes tissue pre-heating before the cutting processes and        tissue rehydration during the cutting process;    -   Controlling the tissue volume in or around the cut zone to        create more favorable conditions for tissue cutting;    -   Controlling energy and power delivery to allow vaporization to        enhance and or contribute to the cutting process. For example,        controlling the energy delivery to vaporize both intracellular        and/or extracellular fluids and/or other cellular materials and        foreign fluids within the cut zone;    -   Fragmenting the tissue or cellular material during the cutting        process to enhance tissue division in the cut zone;    -   Melting or collapsing the tissue or cellular material during the        cutting process to enhance tissue division in the cut zone. For        example, melting the tissue to create internal stress within the        tissue to induce tissue tearing;    -   Controlling tissue temperature, arcing, power density and/or        current density during the cutting process to enhance tissue        division in the cut zone;    -   Applying various mechanical elements to the tissue such as        pressure, tension and/or stress (either internally or        externally) to enhance the cutting process; and    -   Utilizing various other tissue treatments before or during the        cutting process to enhance tissue cutting, e.g., tissue sealing,        cauterization and/or coagulation.

Many of the electrode assemblies described herein employ one or more ofthe above-identified factors for enhancing tissue division. For example,many of the electrode assemblies described herein utilize variousgeometrical configurations of electrodes, cutting elements, insulators,partially conductive materials and semiconductors to produce or enhancethe cutting effect. In addition, by controlling or regulating theelectrosurgical energy from the generator in any of the ways describedabove, tissue cutting may be initiated, enhanced or facilitated withinthe tissue cutting zone. For example, it is believed that thegeometrical configuration of the electrodes and insulators may beconfigured to produce a so-called “cut effect”, which may be directlyrelated to the amount of vaporization or fragmentation at a point in thetissue or the power density, temperature density and/or mechanicalstress applied to a point in the tissue. The geometry of the electrodesmay be configured such that the surface area ratios between theelectrical poles focus electrical energy at the tissue. Moreover, thegeometrical configurations of the electrodes and insulators may bedesigned such that they act like electrical sinks or insulators toinfluence the heat effect within and around the tissue during thesealing or cutting processes.

Referring now to the various figures, FIG. 1A depicts a bipolar forceps10 for use in connection with endoscopic surgical procedures and FIG. 1Bdepicts an open forceps 100 contemplated for use in connection withtraditional open surgical procedures. For the purposes herein, either anendoscopic instrument or an open instrument may be utilized with theelectrode assembly described herein. Obviously, different electrical andmechanical connections and considerations apply to each particular typeof instrument, however, the novel aspects with respect to the electrodeassembly and its operating characteristics remain generally consistentwith respect to both the open or endoscopic designs.

FIG. 1A shows a bipolar forceps 10 for use with various endoscopicsurgical procedures and generally includes a housing 20, a handleassembly 30, a rotating assembly 80, a switch assembly 70 and anelectrode assembly 105 having opposing jaw members 110 and 120 whichmutually cooperate to grasp, seal and divide tubular vessels andvascular tissue. More particularly, forceps 10 includes a shaft 12 whichhas a distal end 16 dimensioned to mechanically engage the electrodeassembly 105 and a proximal end 14 which mechanically engages thehousing 20. The shaft 12 may include one or more known mechanicallyengaging components which are designed to securely receive and engagethe electrode assembly 105 such that the jaw members 110 and 120 arepivotable relative to one another to engage and grasp tissuetherebetween.

The proximal end 14 of shaft 12 mechanically engages the rotatingassembly 80 (not shown) to facilitate rotation of the electrode assembly105. In the drawings and in the descriptions which follow, the term“proximal”, as is traditional, will refer to the end of the forceps 10which is closer to the user, while the term “distal” will refer to theend which is further from the user. Details relating to the mechanicallycooperating components of the shaft 12 and the rotating assembly 80 aredescribed in commonly-owned U.S. patent application Ser. No. 10/460,926entitled “VESSEL SEALER AND DIVIDER FOR USE WITH SMALL TROCARS ANDCANNULAS” filed on Jun. 13, 2003 the entire contents of which areincorporated by reference herein.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50 to actuate the opposing jawmembers 110 and 120 of the electrode assembly 105 as explained in moredetail below. Movable handle 40 and switch assembly 70 are of unitaryconstruction and are operatively connected to the housing 20 and thefixed handle 50 during the assembly process. Housing 20 is constructedfrom two components halves 20 a and 20 b which are assembled about theproximal end of shaft 12 during assembly. Switch assembly is configuredto selectively provide electrical energy to the electrode assembly 105.

As mentioned above, electrode assembly 105 is attached to the distal end16 of shaft 12 and includes the opposing jaw members 110 and 120.Movable handle 40 of handle assembly 30 imparts movement of the jawmembers 110 and 120 from an open position wherein the jaw members 110and 120 are disposed in spaced relation relative to one another, to aclamping or closed position wherein the jaw members 110 and 120cooperate to grasp tissue therebetween.

Referring now to FIGS. 1B, an open forceps 100 includes a pair ofelongated shaft portions 112 a and 112 b each having a proximal end 114a and 114 b, respectively, and a distal end 116 a and 116 b,respectively. The forceps 100 includes jaw members 120 and 110 whichattach to distal ends 116 a and 116 b of shafts 112 a and 112 b,respectively. The jaw members 110 and 120 are connected about pivot pin119 which allows the jaw members 110 and 120 to pivot relative to oneanother from the first to second positions for treating tissue. Theelectrode assembly 105 is connected to opposing jaw members 110 and 120and may include electrical connections through or around the pivot pin119. Examples of various electrical connections to the jaw members areshown in commonly-owned U.S. patent application Ser. Nos. 10/474,170,10/116,824, 10/284,562 10/472,295, 10/116,944, 10/179,863 and10/369,894, the contents of all of which are hereby incorporated byreference herein.

Each shaft 112 a and 112 b includes a handle 117 a and 117 b disposed atthe proximal end 114 a and 114 b thereof which each define a finger hole118 a and 118 b, respectively, therethrough for receiving a finger ofthe user. As can be appreciated, finger holes 118 a and 118 b facilitatemovement of the shafts 112 a and 112 b relative to one another which, inturn, pivot the jaw members 110 and 120 from the open position whereinthe jaw members 110 and 120 are disposed in spaced relation relative toone another to the clamping or closed position wherein the jaw members110 and 120 cooperate to grasp tissue therebetween. A ratchet 130 isincluded for selectively locking the jaw members 110 and 120 relative toone another at various positions during pivoting.

More particularly, the ratchet 130 includes a first mechanical interface130 a associated with shaft 112 a and a second mating mechanicalinterface associated with shaft 112 b. Each position associated with thecooperating ratchet interfaces 130 a and 130 b holds a specific, i.e.,constant, strain energy in the shaft members 112 a and 112 b which, inturn, transmits a specific closing force to the jaw members 110 and 120.It is envisioned that the ratchet 130 may include graduations or othervisual markings which enable the user to easily and quickly ascertainand control the amount of closure force desired between the jaw members110 and 120.

As best seen in FIG. 1B, forceps 100 also includes an electricalinterface or plug 200 which connects the forceps 100 to a source ofelectrosurgical energy, e.g., an electrosurgical generator (not shown).Plug 200 includes at least two prong members 202 a and 202 b which aredimensioned to mechanically and electrically connect the forceps 100 tothe electrosurgical generator 500 (See FIG. 1A). An electrical cable 211extends from the plug 200 and securely connects the cable 211 to theforceps 100. Cable 211 is internally divided within the shaft 112 b totransmit electrosurgical energy through various electrical feed paths tothe electrode assembly 105.

One of the shafts, e.g., 112 b, includes a proximal shaftconnector/flange 119 which is designed to connect the forceps 100 to asource of electrosurgical energy such as an electrosurgical generator500. More particularly, flange 119 mechanically secures electrosurgicalcable 211 to the forceps 100 such that the user may selectively applyelectrosurgical energy as needed.

Referring now to FIG. 2, an electrode assembly 205 for use with aninstrument for sealing and cutting vessels and/or tissue is shown. FIG.2 discloses a pair of opposing first 210 and second 220 jaw members atleast one of which is movable. The jaw members 210, 220 are disposed inspaced relation relative to one another and cooperate to grasp tissue.

Each jaw member 210, 220 includes at least one electrically conductivetissue sealing surfaces 212 a, 212 b, 222 a, 222 b extending along alength of the jaw member 210, 220. Each tissue sealing surface 212 a,212 b, 222 a, 222 b is adapted to connect to a source of electrosurgicalenergy (e.g. an electrosurgical generator) such that the tissue sealingsurfaces 212 a, 212 b, 222 a, 222 b are capable of conductingelectrosurgical energy through tissue held therebetween to effect aseal.

An insulator 213, 223 is disposed adjacent to electrically conductivesealing surfaces 212 a, 212 b, 222 a, 222 b. The insulator or insulativematerial may be of any suitable composition. Some possible insulatorsinclude, but are not limited to, glass, polymeric, and ceramicmaterials. An additional insulator (not shown) may be included tofurther isolate the sealing heat from influencing (e.g., minimize thepropagation of heat) during the sealing process.

First jaw member 210 includes an electrically conductive cutting element227 disposed within the insulator 213 of the first jaw member 210. Theelectrically conductive cutting element 227 is disposed in generalvertical registration to the insulator 223 on the second jaw member 220.Sealing plates 212 a and 212 b of jaw member 210 are both configured toinclude a U-shaped sealing section 212 a′ and 212 b′, respectively,which contacts the tissue for sealing purposes and are both alsoconfigured to include an L-shaped flange portion 215 a and 215 b,respectively, which each extend from a respective inner leg 212 a″ and212 b″ of the U-shaped sealing sections 212 a′ and 212 b′. Flangeportions 215 a and 215 b are dimensioned to extend beyond the U-shapedsealing sections 212 a′ and 212 b′ of jaw member 210 towards jaw member220. The parallel flange sections 215 a′ and 215 b′ may be dimensionedto control the gap distance between sealing surfaces 212 a, 222 a and212 b, 222 b, respectively, during the sealing process to within a rangeof about 0.001 inches to about 0.006 inches. The arrangement of flangeportions 215 a and 215 b and cutting electrode 227 define a cutting zone228 disposed inwardly of flange portions 215 a and 215 b.

Interposed between each respective flange portion 215 a and 215 b andinner leg portion 212 a″ and 212 b″ is an insulative material 240 a and240 b, respectively. The insulative materials 240 a and 240 b aredimensioned to have profiles designed to reduce stray currents and heatdissipation inwardly towards the cutting zone 228 during the sealingprocess.

Electrically conductive tissue sealing surfaces 212 a, 212 b of jawmember 210 may extend towards jaw member 220 as shown in FIG. 2. Thiscreates a design that is symmetrical about the cutting element 227. Thisisolates the cut zone 228 with a high impedance pinch point. Although asymmetrical design is depicted, alternate designs may be implemented aswill be discussed hereinafter.

Cutting element 227 and the pair of spaced apart electrically conductivesealing surfaces 212 a, 212 b on the first jaw member 210 may beenergized to the same potential during a sealing process andelectrically conductive sealing surfaces 212 a, 212 b on the first jawmember 210 are energized to a different potential from the correspondingelectrically conductive sealing surfaces 222 a, 222 b on the second jawmember 220 such that electrosurgical energy can be transferred throughthe tissue to effect a tissue seal. This arrangement eliminates chargingof the cutting element 227 by maintaining the same potential betweencutting element 227 and the at least one electrically conductive sealingsurfaces 212 a, 212 b on the first jaw member 210.

During cutting, cutting element 227 maintains the same potential duringa cutting process; however, electrically conductive sealing surfaces 212a, 212 b on the first jaw member 210 and the corresponding at least oneelectrically conductive sealing surfaces 222 a, 222 b on the second jawmember 220 are energized to a different potential than the cuttingelement 227 such that electrosurgical energy can be transferred throughthe tissue to effect a tissue cut.

Using this configuration, only electrically conductive sealing surfaces212 a, 212 b on the first jaw member 210 need to switch polarity to gofrom sealing to cutting. Moreover, this design may also isolate the cutzone 228 from the seal leaving less effected tissue for the cuttingcycle.

Referring now to FIG. 3, an alternate embodiment of the vessel sealinginstrument of the present disclosure having one isolated cut zone 328 isshown. In this embodiment one of the isolated cut zones of FIG. 2 hasbeen removed in order to reduce space. Sealing plates 312 a of jawmember 310 is configured to include a U-shaped sealing section 312 a′,which contacts the tissue for sealing purposes, and is also configuredto include an L-shaped flange portion 315, which extends from arespective inner leg 312 a″ of the U-shaped sealing section 312 a′.Sealing plate 322 a, 312 b and 322 b are all generally U-shaped. Flangeportion 315 a is dimensioned to extend beyond the U-shaped sealingsection 312 a′ of jaw member 310 towards jaw member 320. Like the flangeportions 215 a and 215 b above, flange portion 315 may be dimensioned tocontrol the gap distance between sealing surface during the sealingprocess. Flange 315 and the cutting electrode 327 define a cutting zone328 disposed therebetween.

Interposed between flange portion 315 a and inner leg portion 312 a″ ofsealing plate 312 a is an insulative material 340. The insulativematerial 340 is dimensioned to have a profile designed to reduce straycurrents and heat dissipation inwardly towards the cutting zone 328during the sealing process. Insulator 313 also includes a first portion313 a that extends between flange 315 and cutting element 327 to a pointin general horizontal registration with the U-shaped portion 312 a′ ofsealing plate 312 a. A second portion 313 b is interposed betweencutting element 327 and sealing plate 312 b but is recessed with respectto sealing plate 312 b. Arranging the insulator 313 a in this fashionmay enhance the cutting effect.

This design results in an isolated cut zone 328 and a non-isolatedcutting zone 329. The polarization is the same as that in FIG. 2. Thisdesign does not eliminate the charge and heat influence during sealing;however, the dimensions of the instrument may be reduced by having oneisolated cut zone 328.

The cutting and sealing processes may be automatically controlled by anelectrosurgical energy source, such as an electrosurgical generator.Moreover, the potential of electrically conductive tissue sealingsurface 312 of the first jaw member 310 and the potential of the cuttingelement 327 are independently activatable by the surgeon. A sensor (notshown) may be used for determining seal quality prior to cutting.

Referring now to FIGS. 4-7, alternate geometries of the sealconfiguration of an electrode assembly 405 of the present disclosure aredescribed. FIG. 4 shows first and second jaw members 410, 420 includinginsulator or insulative material 413. Cutting element 427 is operativelyconnected to first jaw member 410. In this arrangement cutting element427 is given a neutral polarity while sealing surfaces 412 a, 412 b arepositive and sealing surfaces 422 a and 422 b are negative. Thepolarities of sealing surfaces 412 and 422 may be reversed as long asthe cutting element 427 maintains a neutral polarity. During the cuttingprocess the cutting electrode 427 is provided with an electricalpotential and sealing surfaces 412 a, 412 b, 422 a and 422 b areprovided with either the same, neutral or different potentials dependingupon a particular purpose. Commonly-owned U.S. patent application Ser.No. 10/932,612 discloses various electrical arrangements for sealing andcutting tissue with the sealing and cutting electrodes, the entirecontents being incorporated herein.

FIG. 5 discloses an alternate embodiment of the seal configuration of anelectrode assembly 505 having a second cutting element 537 operativelyconnected to the second jaw member 520 in vertical registration withcutting element 527. The second cutting element 537 may be polarized tothe same potential as the cutting element 527. In this arrangementcutting elements 527, 537 are both given a neutral polarity whilesealing surfaces 512 a, 512 b are positive and sealing surfaces 522 aand 522 b are negative. The polarities of sealing surfaces 512 and 522may be reversed as long as the cutting elements 527, 537 maintain theirneutral polarity.

FIG. 6 shows yet another embodiment of the seal configuration of anelectrode assembly 605 having one sealing surface 612 on the first jawmember 610 and one sealing surface 622 on the second jaw member 620. Acutting element 637 is shown disposed upon the second jaw member 620.Although cutting element 637 is shown on the second jaw member 620, itmay be placed on the first jaw member 610 as well. In this arrangementcutting element 637 is given a neutral polarity while sealing surface612 is positive and sealing surface 622 is negative. The polarities ofsealing surfaces 612 and 622 may be reversed as long as the cuttingelement 637 maintains a neutral polarity. First jaw member 610 shows aninsulator 613 having a generally rounded configuration that extendsbeyond the periphery of jaw member 620. Other suitable geometries arealso envisioned.

FIG. 7 discloses an embodiment having cutting elements 727, 737 on boththe first and second jaw members 710, 720. This embodiment also includesone sealing surface 712 on the first jaw member 710 and one sealingsurface 722 on the second jaw member 720. In this arrangement cuttingelements 727, 737 are both given a neutral polarity while sealingsurface 712 is positive and sealing surface 722 is negative. Thepolarities of sealing surfaces 712 and 722 may be reversed as long asthe cutting elements 727, 737 maintain their neutral polarity. In thisarrangement, insulators 713 and 723 align in general verticalregistration on the outside of cutting elements 727 and 737.

In the embodiments described herein the cutting element may besubstantially dull and only capable of cutting tissue throughelectrosurgical activation. Moreover, the cutting element may bedisposed within the insulator of the first or second jaw member. Asmentioned hereinbefore the potential of the cutting element and theelectrically conductive tissue sealing surfaces may be altered dependingupon a particular desired surgical effect.

As can be appreciated, the various geometrical configurations andelectrical arrangements of the aforementioned electrode assemblies allowthe surgeon to initially activate the two opposing electricallyconductive tissue contacting surfaces and seal the tissue and,subsequently, selectively and independently activate the cutting elementand one or more tissue contacting surfaces to cut the tissue utilizingthe various above-described and shown electrode assembly configurations.Hence, the tissue is initially sealed and thereafter cut withoutre-grasping the tissue.

However, the cutting element and one or more tissue contacting surfacesmay also be activated to simply cut tissue/vessels without initiallysealing. For example, the jaw members may be positioned about tissue andthe cutting element may be selectively activated to separate or simplycoagulate tissue. This type of alternative embodiment may beparticularly useful during certain endoscopic procedures wherein anelectrosurgical pencil is typically introduced to coagulate and/ordissect tissue during the operating procedure.

A switch 70 (FIG. 1A) may be employed to allow the surgeon toselectively activate one or more tissue contacting surfaces or thecutting element independently of one another. This allows the surgeon toinitially seal tissue and then activate the cutting element by simplyactivating the switch. Rocker switches, toggle switches, flip switches,dials, etc. are types of switches that can be commonly employed toaccomplish this purpose.

These switches can be placed anywhere on the instrument or may beconfigured as a remote switch, e.g., handswitch or footswitch. Theswitch may also cooperate with a smart sensor 501 (or smart circuit,computer, feedback loop, etc.) that automatically triggers the switch tochange between the “sealing” mode and the “cutting” mode upon thesatisfaction of a particular parameter. For example, the smart sensormay include a feedback loop that indicates when a tissue seal iscomplete based upon one or more of the following parameters: tissuetemperature, tissue impedance at the seal, change in impedance of thetissue over time and/or changes in the power or current applied to thetissue over time. An audible or visual feedback monitor may be employedto convey information to the surgeon regarding the overall seal qualityor the completion of an effective tissue seal. A separate lead may beconnected between the smart sensor and the generator for visual and/oraudible feedback purposes.

The generator 500 delivers energy to the tissue in a pulse-likewaveform. It has been determined that delivering the energy in pulsesincreases the amount of sealing energy that can be effectively deliveredto the tissue and reduces unwanted tissue effects, such as charring.Moreover, the feedback loop of the smart sensor can be configured toautomatically measure various tissue parameters during sealing (i.e.,tissue temperature, tissue impedance, current through the tissue) andautomatically adjust the energy intensity and number of pulses as neededto reduce various tissue effects, such as charring and thermal spread.

It has also been determined that RF pulsing may be used to moreeffectively cut tissue. For example, an initial pulse from the cuttingelement through the tissue (or the tissue contacting surfaces throughthe tissue) may be delivered to provide feedback to the smart sensor forselection of the ideal number of subsequent pulses and subsequent pulseintensity to effectively and consistently cut the amount or type oftissue with minimal effect on the tissue seal. If the energy is notpulsed, the tissue may not initially cut but desiccate since tissueimpedance remains high during the initial stages of cutting. Byproviding the energy in short pulses, it has been found that the tissueis more likely to cut.

Alternatively, a switch may be configured to activate based upon adesired cutting parameter and/or after an effective seal is created orhas been verified. For example, after effectively sealing the tissue,the cutting element may be automatically activated based upon a desiredend tissue thickness at the seal.

As mentioned in many of the above embodiments, upon compression of thetissue, the cutting element may act as a stop member and create a gap“G” between the opposing conductive tissue contacting surfaces.Particularly with respect to vessel sealing, the gap distance may be inthe range of about 0.001 to about 0.006 inches. As mentioned above, thegap distance “G” and clamping pressure between conductive surfaces aretwo important mechanical parameters that need to be properly controlledto assure a consistent and effective tissue seal. The surgeon activatesthe generator to transmit electrosurgical energy to the tissuecontacting surfaces and through the tissue to effect a seal. As a resultof the unique combination of the clamping pressure, gap distance “G” andelectrosurgical energy, the tissue collagen melts into a fused mass withlimited demarcation between opposing vessel walls.

Once sealed, the surgeon activates the cutting element to cut thetissue. As mentioned above, the surgeon does not necessarily need tore-grasp the tissue to cut, i.e., the cutting element is alreadypositioned proximate the ideal, center cutting line of the seal. Duringthe cutting phase, highly concentrated electrosurgical energy travelsfrom the cutting element through the tissue to cut the tissue into twodistinct halves. As mentioned above, the number of pulses required toeffectively cut the tissue and the intensity of the cutting energy maybe determined by measuring the seal thickness and/or tissue impedanceand/or based upon an initial calibrating energy pulse which measuressimilar parameters. A smart sensor (not shown) or feedback loop may beemployed for this purpose.

The forceps may be configured to automatically cut the tissue oncesealed or the instrument may be configured to permit the surgeon toselectively divide the tissue once sealed. Moreover, an audible orvisual indicator (not shown) may be triggered by a sensor (not shown) toalert the surgeon when an effective seal has been created. The sensormay, for example, determine if a seal is complete by measuring one oftissue impedance, tissue opaqueness and/or tissue temperature.Commonly-owned U.S. application Ser. No. 10/427,832 which is herebyincorporated by reference herein describes several electrical systemswhich may be employed to provide positive feedback to the surgeon todetermine tissue parameters during and after sealing and to determinethe overall effectiveness of the tissue seal.

The electrosurgical intensity from each of the electrically conductivesurfaces and cutting elements is selectively or automaticallycontrollable to assure consistent and accurate cutting along thecenterline of the tissue in view of the inherent variations in tissuetype and/or tissue thickness. Moreover, the entire surgical process maybe automatically controlled such that after the tissue is initiallygrasped the surgeon may simply activate the forceps to seal andsubsequently cut tissue. In this instance, the generator may beconfigured to communicate with one or more sensors (not shown) toprovide positive feedback to the generator during both the sealing andcutting processes to insure accurate and consistent sealing and divisionof tissue. As mentioned above, commonly-owned U.S. patent applicationSer. No. 10/427,832 discloses a variety of feedback mechanisms which maybe employed for this purpose.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the present disclosure. For example, cutting element may bedimensioned as a cutting wire that is selectively activatable by thesurgeon to divide the tissue after sealing. More particularly, a wire ismounted within the insulator between the jaw members and is selectivelyenergizable upon activation of the switch.

The forceps may be designed such that it is fully or partiallydisposable depending upon a particular purpose or to achieve aparticular result. For example, the electrode assembly may beselectively and releasably engageable with the distal end of the shaftand/or the proximal end of shaft may be selectively and releasablyengageable with the housing and the handle assembly. In either of thesetwo instances, the forceps would be considered “partially disposable” or“reposable”, i.e., a new or different electrode assembly (or electrodeassembly and shaft) selectively replaces the old electrode assembly asneeded.

The electrode assembly could be selectively detachable (i.e., reposable)from the shaft depending upon a particular purpose, e.g., specificforceps could be configured for different tissue types or thicknesses.Moreover, a reusable forceps could be sold as a kit having differentelectrodes assemblies for different tissue types. The surgeon simplyselects the appropriate electrode assembly for a particular tissue type.

The forceps could also include a mechanical or electrical lockoutmechanism that prevents the sealing surfaces and/or the cutting elementfrom being unintentionally activated when the jaw members are disposedin the open configuration.

Although the subject forceps and electrode assemblies have beendescribed with respect to preferred embodiments, it will be readilyapparent to those having ordinary skill in the art to which itappertains that changes and modifications may be made thereto withoutdeparting from the spirit or scope of the subject devices. For example,although the specification and drawing disclose that the electricallyconductive surfaces may be employed to initially seal tissue prior toelectrically cutting tissue in one of the many ways described herein,the electrically conductive surfaces may also be configured andelectrically designed to perform any known bipolar or monopolarfunction, such as electrocautery, hemostasis, and/or desiccationutilizing one or both jaw members to treat the tissue. Moreover, the jawmembers in their presently described and illustrated formation may beenergized to simply cut tissue without initially sealing tissue, whichmay prove beneficial during particular surgical procedures. Moreover,the various geometries of the jaw members, cutting elements, insulatorsand semi-conductive materials and the various electrical configurationsassociated therewith may be utilized for other surgical instrumentationdepending upon a particular purpose, e.g., cutting instruments,coagulation instruments, electrosurgical scissors, etc.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

The invention claimed is:
 1. An electrode assembly for use with aninstrument for sealing and/or cutting tissue, the electrode assemblycomprising: a pair of opposing first and second jaw members moveablefrom a first space position relative to one another to a second, closedposition for gripping tissue, each of the jaw members including at leastone electrically conductive tissue sealing element extending along alength thereof, each of the at least one electrically conductive tissuesealing elements having a U-shaped sealing section configured to contacttissue and being adapted to connect to a source of electrosurgicalenergy such that the at least one electrically conductive tissue sealingelements are capable of conducting electrosurgical energy through tissueheld therebetween; wherein at least one of the first and second jawmembers includes at least one L-shaped flange portion configured todefine a central cutting zone; an insulator disposed adjacent to each ofthe at least one electrically conductive tissue sealing elements; thefirst jaw member including an electrically conductive cutting elementdisposed within the insulator of the first jaw member, the electricallyconductive cutting element disposed in general vertical registration tothe insulator on the second jaw member and within the central cuttingzone; wherein the at least one L-shaped flange portion abuts theopposing insulator when the jaw members are disposed in the closedposition to define a gap distance between the U-shaped sealing sectionsof the first and second jaw members; wherein the cutting element and theat least one electrically conductive tissue sealing elements on thefirst jaw member are energized to a first potential during a sealingprocess, wherein the first potential is different than a secondpotential energizing the at least one electrically conductive tissuesealing element on the second jaw member such that the electrosurgicalenergy can be transferred through the tissue to effect a tissue seal;and the cutting element is configured to maintain the same firstpotential during a cutting process and the at least one electricallyconductive tissue sealing element on the first jaw member and thecorresponding at least one electrically conductive tissue sealingelement on the second jaw member are energized to the second potentialsuch that the electrosurgical energy can be transferred through thetissue to effectively cut the tissue and wherein the at least oneL-shaped flange portion restricts the size of the resulting cuttingregion around the cutting element during the cutting process.
 2. Theelectrode assembly according to claim 1, wherein the cutting and sealingprocesses are automatically controlled by the electrosurgical energysource.
 3. The electrode assembly according to claim 1, wherein thepotential of the at least one electrically conductive tissue sealingelement of the first jaw member and the potential of the cutting elementare independently activatable by a surgeon.
 4. The electrode assemblyaccording to claim 1, further comprising a sensor for determining sealquality prior to the cutting process.
 5. The electrode assemblyaccording to claim 1, wherein the cutting element is substantially dulland only capable of cutting tissue through electrosurgical activation.6. The electrode assembly according to claim 1, wherein the potentialsof the cutting element and the electrically conductive tissue sealingelements are selectively alterable.
 7. The electrode assembly accordingto claim 1, wherein each of the jaw members includes only oneelectrically conductive tissue sealing element.
 8. An electrode assemblyfor use with an instrument for sealing and/or cutting tissue, theelectrode assembly comprising: a pair of opposing first and second jawmembers moveable from a first space position relative to one another toa second, closed position for gripping tissue, each of the jaw membersincluding at least one electrically conductive tissue sealing elementextending along a length thereof, each of the at least one electricallyconductive tissue sealing elements having a U-shaped sealing sectionconfigured to contact tissue and being adapted to connect to a source ofelectrosurgical energy such that the at least one electricallyconductive tissue sealing elements are capable of conductingelectrosurgical energy through tissue held therebetween; wherein atleast one of the first and second jaw members includes at least oneL-shaped flange portion configured to define a central cutting zone; aninsulator disposed adjacent to each of the at least one electricallyconductive tissue sealing elements; the first jaw member including anelectrically conductive cutting element disposed within the insulator ofthe first jaw member, the electrically conductive cutting elementdisposed in general vertical registration to the insulator on the secondjaw member and within the central cutting zone; wherein the at least oneL-shaped flange portion abuts the opposing insulator when the jawmembers are disposed in the closed position and the at least oneL-shaped flange portion is adapted to control a gap distance between theat least one electrically conductive tissue sealing surfaces of thefirst and second jaw members; a second insulator adjacent the at leastone L-shaped flange portion dimensioned to reduce stray currents andheat dissipation inwardly towards the central cutting zone; wherein thecutting element and the at least one electrically conductive tissuesealing element on the first jaw member are energized to a firstpotential during a sealing process and the at least one electricallyconductive sealing element on the second jaw member are energized to asecond potential, where the second potential is different from the firstpotential applied to the at least one electrically conductive tissuesealing element on the first jaw member such that the electrosurgicalenergy can be transferred through the tissue to effect a tissue seal;and wherein the cutting element is configured to maintain the same firstpotential during a cutting process and the at least one electricallyconductive tissue sealing element on the first jaw member and thecorresponding at least one electrically conductive tissue sealingelement on the second jaw member are energized to the second potentialsuch that the electrosurgical energy can be transferred through thetissue to effectively cut the tissue wherein the at least one L-shapedflange portion restricts the size of the resulting cutting region duringthe cutting process.
 9. The electrode assembly according to claim 8,wherein the at least one L-shaped flange portion and the cutting elementdefine the cutting zone disposed inwardly of the at least one L-shapedflange portion.